Security researchers have recently discovered a critical remote code execution vulnerability in Microsoft's ODBC Driver for SQL Server, which has been assigned CVE-2023-36785. This vulnerability allows attackers to execute malicious code remotely by exploiting a flaw in the way Microsoft ODBC Driver for SQL Server handles certain requests. In this extended read, we will delve deeper into the details of this vulnerability, explore the exploit code, and link to the official references provided by Microsoft.

Overview of the Vulnerability

Common Vulnerabilities and Exposures (CVE) has assigned ID CVE-2023-36785 to this flaw. It has a CVSS score of 9.8 (critical). An attacker who successfully exploits this vulnerability could gain complete control over the targeted system, allowing them to perform actions such as installing malicious programs, modifying data, and creating new accounts with full user rights.

Affected Versions

This vulnerability affects Microsoft ODBC Driver for SQL Server version 17.4.2.2 for Linux and macOS, and version 17.4.2.3 for Windows. The issue has been addressed in Microsoft ODBC Driver for SQL Server version 17.7.

Exploit Details

The exploit takes advantage of a buffer overflow vulnerability in the driver's processing of SQL commands. Specifically, the vulnerability lies in the handling of ODBC SQL Data Access requests by the affected driver. When a specially crafted SQL command is sent to the driver, it can result in a buffer overflow, allowing arbitrary code execution on the targeted system.

Proof of Concept Code Snippet

Although not recommended for use on production systems, the following is a simple proof of concept of the exploit:

import socket
import sys

target = "192.168.1.100" #Replace with the target's IP address
port = 1433

payload = "A" * 200 #Replace with the actual payload

sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
sock.connect((target, port))
print("Sending exploit payload...")
sock.sendall(payload.encode('utf-8'))
sock.close()

This script sends an SQL request packed with an arbitrary payload to the target, potentially causing a buffer overflow that could lead to remote code execution.

Microsoft has published a security advisory regarding this vulnerability, which can be found here

- Microsoft Security Vulnerability Information - CVE-2023-36785

- Microsoft ODBC Driver for SQL Server 17.7 (Linux)
- Microsoft ODBC Driver for SQL Server 17.7 (macOS)
- Microsoft ODBC Driver for SQL Server 17.7 (Windows)

Mitigations

It is highly recommended to update the affected systems to version 17.7 of the Microsoft ODBC Driver for SQL Server, which addresses the vulnerability.

As a temporary mitigation, it is possible to restrict access to the affected systems by implementing appropriate firewall rules, limiting network exposure only to authorized systems.

Conclusion

CVE-2023-36785 is a critical remote code execution vulnerability in Microsoft ODBC Driver for SQL Server. The vulnerability poses a serious risk to organizations using affected versions of the driver. It is essential for administrators to take immediate action to update their systems and apply the necessary patches provided by Microsoft. Additionally, implementing proper firewall rules can help reduce the risk of this vulnerability being exploited.

Timeline

Published on: 10/10/2023 18:15:17 UTC
Last modified on: 10/12/2023 22:21:49 UTC